How to store an excel table into a double String array using apache POI?

Question

I want to save the values from a table in excel and store them into a String[][] variable in order to make it easier to manipulate, here is my code:

public class TakingDataFromExcel {
  public static void main(String[] args) {
    try{
        FileInputStream file = new FileInputStream(new File("C:\\Book1.xls"));
        Workbook workbook = new HSSFWorkbook(file);
        Sheet sheet = workbook.getSheetAt(0);
        String[][] headers= null;
        String value = null;
        for (int i= 0;i < sheet.getPhysicalNumberOfRows(); i++) {
            DataFormatter formatter = new DataFormatter();
            for (int j=0; j<=6;j++) {
                Row row = sheet.getRow(i);
                value = formatter.formatCellValue(row.getCell(j));
                headers[i][j].concat(value.toString()); 
            }
        }     
        System.out.println(headers); 
        System.out.println(sheet.getPhysicalNumberOfRows());
        String[] cdsid=null;
        cdsid=headers[1][1].split(" ");
        for (int x=0; x<cdsid.length;x++) {
            System.out.println(cdsid[x]);
        }
        file.close();
        }catch (Exception e){
        e.printStackTrace();
        }
   }
}

I'm still getting a null pointer exception error but I can´t see where it is. I am open to any suggestions if you think there is is an easier way to do this task.

And here is the error:

java.lang.NullPointerException
at com.ford.samples.TakingDataFromExcel.main(TakingDataFromExcel.java:26)

possible duplicate of What is a Null Pointer Exception, and how do I fix it? — seenukarthi
– seenukarthi, Commented Aug 18, 2015 at 16:19

andrewdleach · Accepted Answer · 2015-08-18 16:21:44Z

1

You never initialize your 2 dimensional String[] .

String[][] headers= null; should be

String[][] headers= new String[SOME_X][SOME_Y]

answered Aug 18, 2015 at 16:21

andrewdleach

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Comments

Captain Man · Accepted Answer · 2015-08-18 17:50:50Z

0

getPhysicalNumberOfRows() will just count the number of rows in the sheet that are defined. You are iterating over rows assuming that they are sequential. Is it possible that you have an empty row in your spreadsheet and getRow(j) is returning null?

You can try something like this:

Iterator<Row> rowIt = sheet.rowIterator();
while (rowIt.hasNext()) {
  Row row = rowIt.next();           
}

edited Aug 18, 2015 at 17:50

Captain Man

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answered Aug 18, 2015 at 16:30

JeredM

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1 Comment

Josué Almonasi Over a year ago

thanks, I didn't think in that case before, now I will consider when a row is empty.

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